BBC Wildlife Magazine
Mike Dilger’s wildlife watching
In his series of great places to watch wildlife in the UK, the star of BBC One’s The One Show this month turns our attention to the benefits of blanket bogs for nature and the environment.
Blanket bogs are brimming with life
Bleak, frequently shrouded in low cloud and with rain never far away, blanket bogs initially appear to be desolate and forsaken places. Yet these vast, treeless landscapes are at last becoming more widely appreciated. The UK holds around 13 per cent of the world’s surviving blanket bog, which – you might be surprised to learn – covers just under a tenth of our total landmass. These peaty wildernesses are also crucial for both conserving a range of declining species and helping to slow down the juggernaut of climate change.
Blanket bogs began to form here about 7,000 years ago, when Britain’s climate became wetter and warmer. The crucial factor in bog formation is for rainfall to be higher than the loss of water through evaporation and via transpiration from plants. These perennially moist conditions favour the growth of bog mosses, such as sphagnum, which turn into peat when they die back. Over time, accumulated layers of peat gradually create a barrier between the bog vegetation and both groundwater and the underlying bedrock. Since the only source of water is rainfall, the bog becomes progressively more acidic and even lower in nutrients.
Blanket bogs extend from Devon in the south to Shetland in the north, but are at their most extensive and widespread in the west and north. Sometimes, despite being considered an upland habitat, they even occur down to sea level where drainage is poor. Many blanket bogs are considered semi-natural, as ultimately they formed due to the forestfelling actions of our ancestors. Tree removal causes waterlogging, so favours bog formation.
But certainly in Scotland’s Flow Country, which covers swathes of Caithness and Sutherland, the cool, wet climate is thought to have driven the natural development of the region’s immense blanket bogs. Distinctive peaty pools, separated by drier hummocks and verdant sphagnum ‘lawns’, create a complex mosaic that, from the air,
is reminiscent of M C Escher’s repeatedpattern prints.
The acidic, nutrient-poor conditions mean biodiversity is relatively low, yet this belies the habitat’s considerable wildlife interest. Blanket bogs provide hugely important breeding grounds for a number of wading birds, such as golden plover and greenshank, as well as red-throated diver. Additionally, for those with a penchant for insectivorous plants, bogs are undoubtedly the national headquarters for this specialised group: sundews, butterworts and bladderworts all thrive here. There are fascinating insects, too – from common and azure hawker dragonflies patrolling the pools, to the large heath butterfly, which prefers the swards of cotton-grass.
The good news is that blanket bog still covers around 2.25 million hectares of the UK. Sadly, a huge amount has either been degraded or entirely lost. Though peat cutting has gone on for thousands of years with minimal impact, in recent decades there has been extraction on an industrial scale. Moreover, government tax incentives in the 1970s and 1980s led to the spread of commercial forestry, and bogs that had remained treeless for thousands of years were suddenly drained and planted up with conifers.
It has been calculated that the world’s peatlands, despite covering 3 per cent of its land area, hold nearly 30 per cent of all terrestrial carbon. As a result, considerable effort is now being put into the science of bog restoration. By removing nonnative conifers and blocking drains, the landscape can be ‘rewetted’ and wildlife is returning to places where it has not been recorded in decades.
When visiting blanket bogs, remember that many of them experience four seasons in one day, even in high summer, so come prepared for any meteorological eventuality. And, as sphagnum lawns can be treacherous, stick to the well-trodden routes or boardwalks.
The world’s peatlands, despite covering 3 per cent of its land area, hold nearly 30 per cent of all terrestrial carbon.